Animal Phenotyping Core PROJECT SUMMARY/ABSTRACT Rodent models of obesity have provide invaluable to the study of obesity and to the work carried out by NYONRC investigators. To meet the growing needs of Center researchers, the proposed NYONRC Animal Phenotyping Core (APC) reflects a significant expansion of the Animal Energy Balance Core (Einstein) and integration with the animal component of the Adipose Tissue Core (Columbia). During the past 4 years of the current cycle, these components of the NYONRC have processed more than 14,000 service requests for 38 NYONRC members supported by 45 grants, and provided additional services to 9 NIH-funded non-NYONRC members. The services offered by the APC have been instrumental in obtaining 19 new or renewed grants, and in the generation of 213 publications. The proposed APC concentrates and coordinates significantly expanded technical and research capabilities of this amalgamated Core. The incorporation of additional animal resources at both the Einstein and Columbia campuses, will significantly increase the user and research base of the NYONRC overall, and of the APC Core in particular. By coordinated application of NYONRC dedicated facilities, and resources and expertise at both Columbia and Einstein, the proposed APC Core will combine sophisticated qualitative and quantitative measurements of ingestive behavior with concurrent assessments of energy expenditure, physical activity, body temperature, and repeatable noninvasive body composition analysis by MRI and MicroCT. Also available are a range of metabolic surgeries, including gastrointestinal bypass, autonomic denervation procedures, and adipose tissue services including: 1) quantifying adipocyte subpopulations (brown, white, beige), in terms of size, variation, and cellular ultrastructure; 2) primary cell isolation and analysis; 3) differentiation of adipocytes and adipose tissue macrophages; and 4) adipose tissue transplantation. This expanded array of services stems from the growing realization that our understanding of the biology of obesity requires simultaneous assessment of energy intake and energy expenditure, and of the means to determine their net effects on energy balance repeatedly in individual animals. The Specific Aims of the APC are to provide state-of-the-art assessments of: 1) Adipose Tissue Morphology & Function, in terms of cellular, histologic and functional analyses; 2) Body Composition, in terms of the total relative fat and lean mass, and whole body anatomical distribution of adipose tissue; 3) Energy intake and Expenditure, including oxygen and CO2 consumption, respiratory quotient, and thermogenesis in brown adipose tissue; and 4) consequences of Metabolic Procedures and Surgeries, designed to illuminate the physiology of weight regulation and obesity pathophysiology, including gastrointestinal bypass, autonomic denervations and central nervous system targeting using viral, optogenetic and chemogenetic approaches..